mac80211: fix sdata locking around __ieee80211_request_smps

My cfg80211/mac80211 locking unification broke the sdata
locking in ieee80211_set_power_mgmt, it needs to acquire
the lock for __ieee80211_request_smps(). Add the locking.
Reported-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -2378,7 +2378,9 @@ static int ieee80211_set_power_mgmt(struct wiphy *wiphy, struct net_device *dev,
 	local->dynamic_ps_forced_timeout = timeout;
 
 	/* no change, but if automatic follow powersave */
+	sdata_lock(sdata);
 	__ieee80211_request_smps(sdata, sdata->u.mgd.req_smps);
+	sdata_unlock(sdata);
 
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS)
 		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);